Rotary selector switch



' ROTARY SELECTOR SWITCH Filed May 24, 1944 2 Sheets-Sheet 1 HMV Riom@ Nov. 12; 1946. H, R, WARNK'E 2,411,013

ROTARY SELECTOR SWI TCH Filed May 24, 1944 2 Sheets-Sheec 2 Patented Nov. 12,1946

ROTARY SELECTOR SWITCH Herbert R. Warnke, East Orange, N. J., assignor to United States Instrument Corporation, East Orange, N. J., a corporation of New Jersey Application May 24, 1944, Serial No. 537,088

8 Claims.

This invention relates to electrical switches and more particularly to a multi-position selector switch for use in inter-communication systems, signal systems and thelike where a compact selector switch enabling connection with one of a multiplicity of circuits is desired.

It is the general object of the present invention to provide a rotary selector switch of a compact design having low contact resistance, large current capacity, rugged construction,'and long life.

More particularly, it is an object of the invention to provide a rotary selector switch having one or more banks or decks oi terminals, the terminals of each bank being arranged in circular spaced relationship, and having a common central terminal and a rotating contact arm with means thereon for maintaining constant sliding engagement with the common terminal and other means thereon for successively engaging the individual terminals as the contact arm is rotated. A particular feature of the invention lies in the provision of a solid silver contact member, carried on the afore-mentioned contact arm, which bridges the space between the annular common terminal and the individual terminals, serving as a direct and short path of high current carrying capacity.

Another feature of the invention lies in the provision of an auxiliary contact arm, electrically connected to the iirst Contact arm and also adapted to engage the individual terminals successively, providing a second current path between the common terminals and the individual terminals. t is also a feature of the invention that the several sliding contact members are of solid coin silver, providing high current-carrying capacity, low contact -resistan-ce and long life. The contact arms are of a metal possessing good resilience and satisfactory conductance, they are adjusted in such a way as to maintain a light but constant spring pressure forcing the silver contact members into rm engagement with the contact portions of the respective terminals, the adjustment being such that the resilience of the contact arms will serve to compensate for any wear of the contact members or terminals.

Other and further features and objects of the invention will be apparent from the description which follows, read in connection with the accompanying drawings, in which:

Figure l is a rear elevation of a switch con.- structed in accordance with the present invention;

Figure 2 is a side elevation of the switch shown in Figure 1;

Figure 3 is a sectional View on line 3-3 of Figure 1;

Figure 4 is a sectional view on line 4 4 of Figure l;

Figure 5 is a View similar to Figure l but with i all of the individual terminals except one omitted for clarity, and with the auxiliary Contact arm broken away to expose the main contact arm;

Figures 6, 7, 8, and 9 are detail views illustrating, in plan, the auxiliary contact arm, the main side view in Figure 2; and

Figure 11 is a sectional view on line II-II of Figure 10.

In order to facilitate an understanding of the invention, reference is made to the embodiment thereof shown in the accompanying drawings, and detailed descriptive language is employed. It will nevertheless be understood that no limitation of the invention is thereby intended and that various changes and alterations are contemplated such as would ordinarily occur to one skilled in the art to which the invention relates.

Referring now to Figures l, 2, and 3, it will be seen that the switch comprises generally a base plate I [l in which a shaft I I is rotatably mounted by means of a bushing I2, a handle I3 being provided for turning the shaft II, and one or more (in the present case, two) generally annular terminal supports i4 of suitable rigid insulating material, such as Bakelite, each of which is provided with a plurality of terminals I5, which may be of bronze coated with silver. The terminals I5 may be secured to the supports I4 by any suitable means, as for example by hollow rivets IE. The outer ends of the terminals I5 are inclined at an obtuse angle to the plane of the support and are apertured to facilitate the securing of conductors thereto. The inner ends of the terminals I5 lie iiat against the adjacent surface of the support I4 and serve as contact portions of the respective terminals, for engagement with the contact means to be described. The supports ill are maintained in spaced relationship by means of the bolts I'I and spacers I8.

That portion of the shaft I I which lies inwardly of the base plate I0 is flattened as at I9 and carries the indexing disk 20 and the rotating contact supports 2|, which latter are comprised of disks of insulating material, such as Bakelite, of substantially the diameter of the central openings in the terminal supports U3. As best seen in Figure 4 a common terminal 22, preferably of bronze, annular in form, is secured to the terminal support li surrounding and partially overlying the central opening of the latter andthe contact support disk 2l which rotates within said central opening. The common terminal 22 is provided with an extension 22 (Figures l and 3) for connection to a conductor.

The main contact arm 23, which is shown in detail in Figure 7, is mounted on .the contact support 2|, and spaced therefrom, by rivets 24, andv carries two sliding contact members 25 and 26, secured thereto in any suitable manner. In the illustrated embodiment the contact members 25 and Z are solid coin silver and are provided on their upper side with integral bosses 25', 26", extending through apertures in the material of the contact arm 23, and upset or peened to secure the contact members to the arm. It will be noted that the downwardly projecting portions of the contact members 25 and 26 are inclined to the major axis of the contact arm whereby they wipe the contact surfaces of the respective terminals over larger areas, reducing wear and at the same time providing a self-cleaning feature. The contact member 2E has two such downwardly projecting portions, one at each end, for engagement with the common terminal 22 and individual terminals l5, respectively, while the contact member 25 also engages the common terminal 22, but not the individual terminals.

A second or auxiliary contact arm 2l, shown in detail in Figure 6 overlies and is secured to the contact arm 23, being secured by the same rivets 24 which fasten the latter to the support member 2 If, and is thus in electrical contact with contact arm 23. The auxiliary contact arm 2l carries acontact member 2S, which is secured to a downturned iiange 25 of the contact arm by means of integral bosses 3S as described above. The contact member 28, like the others, is inclined to the axis of the contact arm, and is adapted to engage only the individual terminals I5, providing an alternate current path between contact arm 23 and the terminals l5. Thus in all there are two silver contact members engaging .the common terminal 22, and two engaging the individual terminals, the latter two engaging the same individual terminal at any given time. Furthermore, the bridge-like contact member 25 provides a short and direct path of high current-carrying capacity between the common terminal and the individual terminals.

The contact arms 23 and 2i are of metal possessing good resilience and satisfactory currentcarrying capacity, for example beryllium copper, and are adjusted to exert a slight constant pressure upon the contact members forcing them into firm engagement with the respective terminals. Due to the length and exibility of the contact arms, this spring pressure, though slight, will take up any wear to which the contact surfaces may be subject during the lifetime of the switch.

'Ilheindexing mechanism, best seen in Figure 10, comprises the toothed disk 2li, secured on the iiattened portion I9 of the shaft l l, levers 3| pivoted as at 32 to the plate H3, cam follower rollers 33 carried by the levers 3 i, and tension springs 34 secured between the free ends of the levers 3l and studs 35 carried by the base plate i0. The valleys formed in the periphery of the disk 20 correspond in number and spacing to the terminals Iv of. thefrespective terminal supports. It will be readily understood that by virtue of the mechanism just described, when the handle I3 is grasped and the shaft turned to a selected position, the disk 20 will be rotated, each successive tooth passing under the rollers 33 forcing the le- 5 vers 3l outwardly against the pressure of the springs 3d, and each successive valley passing under the rollers 33 permitting the levers to swing inwardly again. Thus when the selected position is reached, the rollers 33 are firmly seated in the ,corresponding valley of the disk Z and the switch is firmly maintained in the selected position until positively actuated.

In the illustrated embodiment, the switch of the present invention is especially adapted for an intercommunication or signalling system in which a master station is to be selectively connected with any one of sixteen subordinate stations by means of a two-wire circuit. However, switches constructed in accordance with the invention may be adapted to a wide variety of useful purposes and the number of decks or banks of individual terminals may be multiplied to any desired number in order to meet the particular purpose at hand.

From the foregoing description it will be apparent that the objects enumerated above are achieved by the invention, and a compact, rugged, and eiiicient all-purpose rotary selector switch is provided.

- Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In a multi-position switch, a base plate, a plurality of generally annular terminal plates supported from said base plate in spaced, aligned relation, a plurality of .terminal members supported in circular, spaced relation on each said terminal plate, each said terminal member having -a contact portion, a shaft rotatably mounted in said base plate and extending through the central openings of said terminal platesa, plurality of contact supports carried by said shaft, one said contact support being substantially in the plane of each said terminal plate, a contact 45 arm mounted Ion each Said contact support, a

common terminal mounted on each said terminal plate and having an annular contact portion surrounding the central opening therein, contact means carried on each said contact arm for slid- 50 ably engaging the contact portion of the adjacent .common terminal, and Contact means carried on each said contact arm for successively engaging the contact portions of the .adjacent terminal members as said shaft is rotated.

2. In a multi-position switch, a base plate, a plurality of generally annular terminal plates supported from said base plate in spaced, aligned relation, a plurality of terminal members supported in circular, spaced relation on each said 60 terminal plate, each said terminal member having a contact portion, a shaft rotatably mounted `in said base plate and extending .through the central openings of said terminal plates, a plurality of contact supports carried by said shaft, one said contact support being substantially in the plane of each said terminal plate, a contact arm mounted on each said contact support, a common terminal mounted on each said terminal plate and having .an annular contact portion surrounding the central opening therein, contact means carried on each said contact arm for slidably engaging the contact portion of .the adjacent common terminal, and contact means carried on each said contact arm for successively 75 engaging the contact portions of the adjacent terminal members .as said shaft is rotated, said last contact means being an integral bridge-like member having a portion adapted to slidably engage the contact portion of the adjacent common terminal in all positions of the contact arm, thereby providing a direct and short currentJ path between said common terminal and said terminal members.

3. In a multi-position switch, a base plate, a plurality of generally annular terminal plates supported from said base plate in spaced, aligned relation, a plurality of terminal members supported in circular, spaced relation on each said terminal plate, each said terminal member having a contact portion, a shaft rotatably mounted in said base plate and extending through the central openings of said terminal plates, a plurality of contact supports carried by said shaft, one said contact support being substantially in the plane of each said terminal plate, a contact arm mounted on each said contact support, a common terminal mounted on each said terminal plate and having an annular contact portion surrounding the central opening therein, .contact means carried on each said contact arm for slidably engaging the contact portion of the adjacent common terminal, and contact means carried on each said contact arm for successively engaging the contact portions of the adjacent terminal members as said shaft is rotated, each said contact means being of solid coin silver.

4. In a multi-position switch, a base plate, a plurality of generally annular terminal plates supported from said base plate in spaced, aligned relation, a plurality of terminal members supported in circular, spaced relation on each said terminal plate, each said terminal member having a contact portion, a shaft rotatably mounted in said base plate and extending through the central openings of said terminal plates, a plurality of contact supports carried by said shaft, one said contact support being substanti-ally in the plane of each said terminal plate, a contact arm mounted on each said contact support, a common terminal mounted on each said terminal plate and having an annular contact portion surrounding the central opening therein, contact means carried on each said Contact arm for slidably engaging the contact portion of the adjacent common terminal, con-tact means carried on each said contact arm for successively engaging the contact portions of the adjacent terminal members as said shaft is rotated, and means for indexing said shaft at a plurality of positions corresponding to said terminal members.

5. In a rotary switch according .to claim 1, an auxiliary contact arm carried on each said contact support and electrically connected to the said contact arm thereon, and contact means on each said auxiliary contact arm for successively engaging said adjacent terminal members, thereby providing a second current path between said contact arm and said terminal members.

6. In a rotary switch -according to claim l, an auxiliary contact arm carried on each said contact support and electrically connected to the said contact arm thereon, and contact means on each said auxiliary contact arm for successively engaging said adjacent terminal members, thereby providing a second current path between said contact arm and said terminal members, said last means being of solid coin silver.

7. A rotary switch according to claim 4, said indexing means comprising a toothed disk mounted on and rotatable with said shaft, a lever pivotally mounted on said base plate adjacent said disk, a cam follower carried by said lever and adapted to engage the toothed periphery of said disk, and resilient means acting on said lever for maintaining said cam follower in engagement with sai-d disk.

8. A switch as dened in claim l, each said contact arm being of metal possessing good resilience and satisfactory electrical conductance, and each said contact means being of solid coin silver.

HERBERT R. WARNKE. 

